Yamaha 160 lb engine. 130 hp

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Marc W

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It sounds like basically the same engine as the 3 cylinder snowmobile engine. The people who have worked with these engines prefer the snowmobile engines because it is easier to mount a PSRU on them.

The 3 cylinder engines have worse TV issues than the 4 cylinder engines like the RX-1 and Apex. The 3 cylinders have a reputation for destroying PSRU's. The 4 cylinders are much smoother running and don't weigh any more so they are generally preferred. Some people have reported successful conversions of the 3 cylinders so time will tell.
 
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rv7charlie

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Royal, there's a bunch of info out there (unfortunately, not consolidated in one place) about the R1 & Apex snowmobile engines, which have the same core as the watercraft and bike engines, but, according to the info I've seen, are much easier to adapt. One big advantage is that the R1/Apex has a built-in 1.3--1 reduction, making it much easier to attach a reduction drive with a reasonable ratio.

Look for Mohawk Aero (adapter plate), Sky Trax (wiring harness mods, adapter plate, and an integrated reduction that fits the Apex), Steve Henry (flying the engine), and search the Kitfox and Avid flier forums for info on all the above.

I'd agree with Marc that there's little reason to use the 3 at this point; its built-in countershafts, etc push the weight up to the same weight as the 4s.

If you think 130 hp from 120 lbs is crazy, there's a turbo 3 that's 180HP in a sled, and wait until you see Steve Henry's latest monster. Under 200 lbs FWF and ~350 HP. (Not that I'd consider running that on a daily driver....)

Charlie
 

Royal

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Welll yeah if you boost them things can get crazy. There is a video of a 510 hp 1.5L CRX thats just nuts. Thank you for the info. Maybe make a sticky for all that info.
 

rv7charlie

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I despise facebook, but here you go; Steve Henry's source for his motor:
https://www.facebook.com/EdgePerformanceEPeX/

There are internet rumors that the (highly modded and boosted) engine is making around 600 HP in ground-bound racing trim.

*Please* know that I'm not saying that level makes any sense for a/c use. But 200 lbs FWF for 200 HP truly begs for an airframe designed around it. Installed in an existing airframe to use that cruise potential raises issues of longitudinal stability due to an extremely extended nose, etc. You'd likely see the tail sprouting extra fins, as seen on many turbine conversions.

Charlie
 

rv7charlie

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Ooo, yes! Good thought. Built for that weight engine, and also designed for high cruise speeds. Unfortunately, I won't own one in this life, which requires a 2nd seat. The MII won't qualify; same issues as RVs, etc.
 

Pale Bear

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Anyone have a good feel for the overhaul interval for these? .. my reading, .. I've come across a 300 hour limit. And what would that mean? A total redo?

Thanks
 

Marc W

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Anyone have a good feel for the overhaul interval for these?
I believe that depends on what engine you are talking about. There aren't any high time conversions yet. I don't think anybody has worn one out. Evidence so far indicates that the valves might need to be adjusted at 500 hours on a stock 4 cylinder engine. Some of these have run over 20,000 miles in sleds. I would expect far beyond 300 hours out of a stock engine.

Probably the best source for info is at
Yamaha Aircraft Conversions
: Yamaha Aircraft Conversions
 

Royal

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Yamaha is probably the best engine designers out there. Id love to design a pusher for this engine. Make more sense that way the nose doesnt have to be so **** long. Only hard thing is getting the Rudders far enough back.
 

pfarber

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Yamaha, and has a peak rpm of about 7800

That's a pretty steep reduction. Wonder how it will vibrate at that RPM?

Also 130hp is not really what most E/AB need. 150-180-200 is the sweet spot.

"I need less horsepower" - no pilot ever
 

Marc W

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The 4 cylinders are rated, stock, at 140hp for the RX-1 and 160 or 165hp for the Apex. Installed weight, that is everything, exhaust, radiator, etc is about 180 lbs. A turboed Apex will put out a very conservative 200 hp and installed weight is 200 lbs.
 

rv7charlie

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The sled engine is actually rated at around 10k rpm. There's an internal 1.3-1 reduction between the crank and the output shaft.
'Most' depends on perspective. Not enough for most 2 seat RVs (except the -9 & especially the -12, where it would be great), but more than adequate for most 2 seat tube/fabric, light sport, gyros, flexwing trikes, etc etc. The Apex engine is 160 HP; more than adequate even for 2 seat RVs, but the 150 lb weight reduction on the nose is going to cause w&b grief, plus yaw stability grief. Like BJC said, just about perfect for MM-1, or any of the other F-1 racers that were designed for 200 lb O-200s. Probably a pretty good fit for a VariEze or LongEze, as well.

I have no real desire to use a turbo, but if one is so inclined, you'd have ~180 HP+ available up in cruise altitudes with minimal boost.

As to smooth...I suspect that it would feel like a turbine compared to a Lyc.

Charlie
 

Royal

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If you want smooth you gotta get a straight 6. They are inherently balanced. But obviously they are big and heavy. The balance on a straight 4 is ok. They have tricks they use to balance. The Lycoming engine i compare to the Subaru engines. Very thumpy and inefficient. Yamaha is one of those companies huge companies go to to design an engine they can't do or at least cheaper. Lexus LFA is an example. I watched a video of an airplane design that started with the issues and dangers of flying. It looked at all the issues and fixed or reduced the problems and then designed the plane around it. I think this engine could solve the engine out on take off issues. Seems to be a fatal recurring crash no matter what plane.
 

Pale Bear

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I believe that depends on what engine you are talking about. There aren't any high time conversions yet. I don't think anybody has worn one out. Evidence so far indicates that the valves might need to be adjusted at 500 hours on a stock 4 cylinder engine. Some of these have run over 20,000 miles in sleds. I would expect far beyond 300 hours out of a stock engine.

Probably the best source for info is at
Yamaha Aircraft Conversions
: Yamaha Aircraft Conversions
ooo, .. 20,000 miles .. that's encouraging. So, IF a person would use a 20 MPH average, (I really have no idea) .. that would be a 1000 hour life. That'd be awesome.
 

pfarber

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>I would expect far beyond 300 hours out of a stock engine.

For the right price I would accept a 100 hour engine.
 

Victor Bravo

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If (and hopefully when) these engines are proven out as reliable and safe in long-term aircraft use (honest, I hope so), then it will allow ScaleBirdsScott and his merry band of innovators to create what will become the 21st Century version of the old War Aircraft Replicas aircraft. Half or 60% size kits for replicas of inline engine warbirds, to compliment the line of radial powered airplanes they're working on now. Little P-40's and Spitfires and long-nose FW-190's, Macchi's and Caudrons, and a 1/3 scale single seat Heinkel 111 just because they could :)

I have a good friend who would get very very fired up about a 2/3 scale FW-189 using those engines, he'd probably write a check tomorrow if Scott had a kit to sell him :)
 

Lendo

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The PSRU is chain drive so I suppose the reduction is approx 2/5 :1 for 7000 rpm is Take-off setting which is 2,800 prop RPM. So if that is correct what is cruise Rpm about 6000 rpm?
What sort of chain is it and I would still like to see the damper.
George
 
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